Conventionally, there has been known a liquid processing apparatus that supplies a chemical liquid to a substrate such as a semiconductor wafer or a glass substrate and performs a liquid process thereon.
By way of example, a liquid processing apparatus described in Patent Document 1 includes a chemical liquid tank configured to store a chemical liquid, a spin chuck configured to be rotated while holding a substrate as a target to be processed, and a supply line configured to supply the chemical liquid from the chemical liquid tank to the substrate on the spin chuck.
Further, recently, there has been known a liquid processing apparatus including a collecting line configured to collect a chemical liquid supplied to a substrate and return it back to a chemical liquid tank to reuse the chemical liquid.
Patent Document 1: Japanese Patent Laid-open Publication No. 2006-269668
However, while a chemical liquid supplied to a substrate is collected and supplied to another substrate, the chemical liquid is exposed to air and oxygen is dissolved in the chemical liquid. Thus, wirings formed of metals such as copper on the substrate may be oxidized and corroded by the oxygen in the chemical liquid.